David g



D. G. MCCAA.

SIGNALING METHOD AND APPARATUS.

APPLICATION FILED' MAY 20, I92I.

1,423,345. Patented July 18, 1922.

FIG. 1

Ffa- 2- /Pz C6w Gr :I A IS Se /H KR FIG 3 INVENTOR will @M A TTORNE Y UNITED STATESfPATENT OFFICE.

DAVID G. MUCAA, OF :PALO ALTO, CALIFORNIA, ASSIGNOR OF ONE-HALF TO CORNELIUS D. EHRET, OF PHILADELPHIA, PENNSYLVANIA.

SIGNALING METHOD AND APPARATUS.

Application filed May 20,

To @ZZ 'zo/mm it may concern.'

Be it known that l, DAVID G. MOCAA, a citizen o'E the United States, residing in Palo Alto, county or' Santa Clara, State of (aliiornia. have invented new and useful improvements in Signaling Methods and Apparatus. oi which the following is a specification.

My invention relates to a method of and apparatus tor receiving signals represented byelectro-radiant energy or high frequency oscillations in radio or carrier ivave conductor systems.

ln accordance With my invention, the pre'lerably sustained or undamped high trequency energy .representing the signals operates in conjunction Withlocally produced high frequency oscillations of the same treduency to rproduce great changes in amplitude and therefore more easily readable or recognizable signals, the changes vin amplitude being etlectedbyperiodically, and at preferably suitable audible note-producing frequency, reversing the co-action of the received and locally produced energies.

In accordance With my invention, Without the production of beats. an audiblesignalrepresenting note is produced, the frequency or pitch yot the note being independent of the -frequencies ot the received and locally producedl energies and is dependent upon the frequency ot reversal of the cio-action between the received andV locally produced energies. l

My invention resides in the hereinafter described method and apparatus.

For an illustration oi some of the vterms mv apparatus may take, and For an understanding of my method` reference may be had to the accompanying drawing. in which t Fig. l, is n diagrammatic view of receiving apparatus embodying my invention and yillustrative of a Inode of practicing my method.

Fig. 9, is a fragmentary diagrammatic viciv ot a modification.

Fig. 3 comprises graphs representing a principle oiE my invention.

Referring toFig. l` A is an antenna or other absorbing structure of a radio receivinor systemH or a conductor `extending betweenV transmitting and receiving stations over which hi vch frequency oscillations rcprcsentinor the signals are transmitted.

"Between the structure A and the earth,

Specication of Letters Patent.

Patented July 18, 12322.

serial No. 471,142.

counter-capacity or return conductor E, are connected the loading` or tuning inductance L, the primary P ot an oscillation transfornier, and the variable condenser C. lnductively related to the primary P is the secondary S, in whose circuit are the variable condenser C1 and the primary P1 of an oscillation transformer Whose secondary S1 is connected in circuit with the variable tuning condenser (l2 and alternately With the oscillation transformer primaries P2 and P3 through the medium of the commutator or rotary pole changer structure D comprising circumterentially spaced conducting con# tacts or segments a successively engaging the lizrush Zi connected to one terminal of the secondary S1. Alternate segments s are connected to the slip ringc, and the intervening alternate segments s are connected to the second slip ring c. Upon the slip rings a and c bear brushes connected, respectively, with the primaries P2 and P3. I

lnductivcly related to the primaries P2 and P3 Vis the secondary S2. one of Whose terminals is connected to the grid g of a thermionic device comprising the bulb V. evacuated to any suitable degree, as Well understood in the art, and containing in additioncto the `.g'rid ,7 the cathode or iilament j and the anode w. The cathode f is connected to a point between tho inductance coils Tilvand L2 disposed. respectively, in the and anode circuits. and forming a coupling between. those circuits. A variable condenser C3 is connected across the Windings S2 and Til. ln the anode circuit is the source ot current or battery B and the telephone T, which. 'it will be understood,r can be replaced b v the primary oi` a transformer or other means Jfor coupling the anode circuit tothe grid circuit of a thermionic arnpliiier, it being understood that the number of amplifiers may he made anything' suitable or desirable. Connected across the battery R and telephone T is a variable condenser (l,

rllic operation is as follows:

Sustained or undamped oscillations, representing the signals. exist in the path in which connected the primary P. which nath naav he attuned thereto. The circuit LQ. (l1, P1 is attuned to the frequency of the oscillations. as is also the circuit S1, C. P2 or P.

Simultaneously there are produced by the thermionic device V and its associated circuits high frequency oscillations Whose frequency is made equal to the frequency of the received energy, which frequency is above audibility or supersonic. Unless the pole changer or reversing commutator D is in operation, no sound will be heard in the telephone T. If, however, the commutator D is rotated, the energy of the received oscillations is impressed alternately through primaries P and P3 upon the circuit of the secondary S2. The primaries P2 and P3 are so wound or connected that they influence the secondary S2 in opposite senses, lwhereby when the primary P2, for example, is in circuit with S1 and C2, the received oscillations and the locally produced. oscillations are :Lor example, iswin circuit, and differentially when the'transformer P"vx is in circuit,

.f'lrccordingly, the uni-directional comimnentof the currentin the anode circuit of the valve V isperiodically increased and decreased by the action of the cummutator D, with the result that there is heard a pure note in the telephone or other instriunent T, the pitch or vfrequency ofthe note being de pendent entirely upon the speed of rotation of the commutator D, that is, dependent en.- tireiy upon Athe rate of change of the Vcircuit connections as regards P2,P3, or either of them. And the note or pitch of the sound in the telephone T is not dependent upon the frequency of the received energy nor upon `the frequency of thel locally produced i' A oscillations.

i VIf' the frequency Vof the received oscillations differs from the frequency ofthe locally produced 7' oscillations, beats Vwill be set up, the beat frequency being equal to the difference between the frequencies of the received and locally produced energies. "In suoli case, with `the"commutator D in operation,v the pure note or tone produced when fthe frequencies of the received and locally produced energies are equal is no longer pure, but is more or less ragged or irregular.

` While it ispreferred thatthe local oscillations Vare produced-hy a therinionic oscillator as described in connection with FigJl, it will be understood that tiny invcntionmay be attained by other arrangements-, one of Uridg cumulatively when the primary P2,

which is indicated in Fig. 2, wherein the f vrimaries P2 and P5 controlled b a commul i Y tator,etc., as in Fig. l, are related to the secondaryS2, as described in' connection with Fig. l. In circuit with the secondary S2 is the variable condenser C5 and the secondary S3 of an oscillation transformer whose primary PL is in circuit with the condenser C and the generator or source Gr of alternating current or oscillations whose frequency is made equal to that of the received energy. In a circuit in shunt to theicondenser C5 is connected any suitable detector, as a rectifying crystalor other detector Rin circuit with thetelephone or other instrument T, the latter shunted by a condenser C7.

Here again the action is the same as described in connection withA Fig. l, the primaries PZ'and P3 alternately coming` into co-operation with the secondaries S2 and causing alternate cumulative and. Vdifferential co actions between the received and lo cally producedA` oscillations, with resultant pure' tone or note in the telephone T, the

frequency' of the note depending solely upon the rate of rotation of the commutator, as D. y ln the arrangementsof both Figs. l and 2, with the commutator D at rest, and only one of the primaries P2 or P3 in circuit with S1 and C?, theeflect upon the instrument VT will he simply: the ordinary effect of simple detector action." T-Iowever, 'with the commutator D in rotation the increased changes in amplitude above ldescifciloedvare effected, and simultaneously a note of desired pitch is attained. 'i

The rate of rotation of the commutator D may be made 4anything suitable or desirable,

but is preferably such as to produce a note in the telephone `T of the order of 500, 1000 or more vibrations per second. Y i

What I claim is f l.. The method of receiving oscillations, which Aconsists in locally generating oscillationslof frequency equal to the frequency of the received oscillations, periodically changing the co-action ofthe reY frequency'of the received oscillations, perif odically Areversing the co-action ofthe rehigh frequency y ceived and locally produced oscillations, and subjecting a translating` instrument to the resultant or the received and locally produced oscillations.

lli. The niethod ol receiving high Atrequencv oscillations, which consists in locally generating oscillations oli frequency equal to the frequencyy oi the received oscillations, periodically at audible frequency reversing the cci-action oi? the received and locally produced oscillations, and subjecting a translating` instrument to the resultant ot the received and locally produced oscillations.

Receiving apparatus comprisiiig a wave responsive device, a signaling instrument controlled thereby, a local source of oscillations having a 'frequency equal to the ireq'ueniv oli the` received oscillations, and means periodically changing the co-action of the received oscillations with the locally produced oscillations. i

6. Receiving apparatus comprising a wave responsive device, a signaling instrument controlled thereby, a local source ot oscillations having a :frequency equal to the requency oit the received oscillations, and means periodically at audible frequency changing the co-action of the received oscillations with the locally produced oscillations.

7. Receiving apparatus comprising a wave responsive device, a signaling instrument controlled thereby, a local source of oscillations having a frequency equal to the trequency of the received oscillations, a circuit traversed by the received oscillations, and a switch periodically changing the sense of iniiuence of the oscillations in said circuit upon said wave responsive device.

S. Receiving apparatus comprising a wave responsive device, a signaling instrument controlled thereby, a local source oit oscillations having a frequency equal to the il'requenov ol the received oscillations, a circuit traversed by the received oscillations, and a switch periodically reversing the sense of influence of the oscillations in said circuit upon said wave responsive device.

9. Receiving apparatus comprising a circuit traversed by received oscillations, a pair of primary windings, periodically operating switching mechanism tor bringing said primaries alternately into operative relation with said circuit, a secondary circuit coupled to said primaries, means for produring in said secondary circuit oscillations of a frequency equal to the frequency et the received oscillations, and a signal translating instrument controlled by said secondary circuit.

10. Radio receiving apparatus comprising an absorbing path, a closed circuit coupled to said path, a second circuit coupled to said circuit, a pair of primaries, switching means for bringing said primaries alternately into cri-operative relation with said second circuit, a secondary circuit coupled to said primaries, a source olf oscillations oi." iirerui-cnfy equal to the frequency" oit the received oscillations, and a signaling instrument controlled by said secondary circuit.

11. Receiving apparatus comprising a circuit traversed by received oscillations, thermionic oscillator, a signal translating i strument controlled thereby, and switcniirif means periodically reversing the relation ol1 said circuit to said oscillator.

l2. The method which comprises causing interaction between electrical oscil'A` ions, periodically changing the interaction between said oscillations, and translating the resultant oli the periodically changed interaction between said oscillations.

Thc method which comprises causing interaction between electrical oscillations, periodically reversing the sense ot thc interaction between said oscillations, and translating the resultant ot' the periodically changed interaction beti een said oscillations.

le. The method ol receiving high 'tra quency oscillations, which `conqznises locally generating oscillations and causing them. to interact with the received oscillations, periodically changing the sense ot interaction between said oscillations` and translating the resultant el: the' periodically changed interaction between said oscillations.

15. The method ot receiving high 'trequency oscillations. which consists in locally generating oscillations, subjecting a trans-A lating .instrument to the locally generated and received oscillations, and periodically changing the sense of combination ot said locally generated and received oscillations.

i6. The method of' receiving high Ytrequency oscillations, which consists in locally generating oscillations, subjecting av translating instrument to the locally generated and received oscillations, and periodically changing at audible frequency the sense oit combination ot said locally generated and received oscillations.

17. The combination with a plurality oit sources ot oscillations of the same frequency, o'f a translating instrument, means lor combining said oscillations in their effect upon said instrument, and means Vtor periodically changing at audible 'frequency the sense of combination oiE said oscillations.

18. The combination with a plurality of sources ot oscillations, of a translating instrument, means for combining said oscillations in their eifect upon said instrument, and means lj'or periodically changing the sense of combination of said oscilllations.

19. The combination with a thermionic oscillator comprising an anode, cathode and control electrode, ott' a second source of os- Y cillations controlling the potential of said zio control electrode, and means periodically changing the sense of control by said second. source ol`y oscillations el the potential of said control electrode.

20. rhe combination with. a tlierinionic oscillator comprising an anode, cathode and control electrode, oii a second source oLt oscillations et the saine 'frequency controlling the potential oi said control electrode, and y ineans periodically changing at audible lirequency the sense ol2 control by said second source ol" oscillations ot the potential of said contro] electrode. e

Q'lgvReceiving apparatus comprising a tlierinionic oscillator comprising an anode, cathode and control electrode, a signaltranslating instrument controlled loy said tliermionic device, means effecting control ol said control electroderby the received energy, and means for periodically changing the sense of control of said control electrode by the received energy.

22. Receiving apparatus comprising a `thermionic oscillator comprising an anode,

cathode and cont-rol electrode for producing oscillations 'whose frequency is equal. to the 'frequency o'i the received energy, a signaltranslating instrument controlled. by said thermionic device, means effecting control of said control electrode by the received energy, andmeans for periodically changing at audipacity attuned to the received energy, means s for delivering received energy to said circuit, a local source of oscillations,` means periodically effecting interaction between the locally produced oscillations and oscillatoryenergy Withdrawn from said closed circuit, and a signaling instrument responsive to the periodic interaction oi thereceived energy Vwith said locally produced oscillations.

y Receiving closed circuit 'including i'nductance and ca pacity attuned to the received energy, means 'for delivering received energy to said circuit, a local source of oscillations having a frequency equal to the frequency olv the received energy, means periodically effecting at audible vfrequency interaction between the locally produced oscillations and oscillatory kenergy Withdrawn from saidl closed circuit,

apparatus comprising aA and a signaling instrument responsive to the L periodic interaction of the received energy 'with said locally produced oscillations.

luntestiniony, whereof l have hereunto affixed my signaturethis llth day of May,`

DAVID e. Moorea. 

